Patients receiving lithium treatment must undergo regular assays of lithium levels, since the difference between therapeutic and toxic serum concentration levels of this medication is small. Current assays cannot be conducted at the point of care, and require a blood draw. Some individuals who could benefit from lithium treatment do not have regular access to health care facilities with follow-up capabilities, and also may be reluctant to undergo frequent blood draws. In such cases, particularly in emergencies, such individuals could benefit from a rapid assay of lithium levels performed at the point-of-care (for example, at a psychiatrist's office).
Magnetic resonance spectroscopic measurements of lithium levels in the brain have been obtained in vivo using a dual-tuned high-field MRI systems equipped with special radiofrequency (RF) coils, as described by J-H Lee et al, in a scientific article entitled “4T 7Li 3D MRSI in the brains of bipolar disorder subjects”, published in 2012 in the journal Magnetic Resonance in Medicine (volume 68, issue 2, pages 363-368), incorporated herein by reference.